The potential permanent exhaustion of world natural resources calls for development of alternative sources of energy. Solar power provides an essentially inexhaustible source of energy. However, the intensity of solar radiation on earth is relatively low, and large areas are needed for solar harvesting systems in which sunlight is collected and converted into electricity, typically by photovoltaic (PV) generation means. These systems need rather large initial investments to be constructed, and must therefore run for longest possible time to make profit.
The efficiency of PV cells is permanently growing (currently the best values about 40% have been achieved), that makes them a very attractive means for a direct conversion of sunlight into electricity. However, PV panels have a rather limited resistance to harsh weather conditions. To increase the resistance, PV panels are strengthened by implementing rather thick metal and/or glass plates. This makes PV panels heavy and difficult to transport.
As a consequence of the global warming, extremely heavy hail, storms, and/or hurricanes are more likely to happen. Thus the possibility of damage to solar power systems will be growing. Therefore, providing safety to solar energy systems becomes an important economical issue.
One of the possible solutions to the problem of the long-term weather resistance of solar systems is provided by a collapsible array that can be retracted and stored in a protective housing during a harsh weather (strong wind, hail, etc.), and deployed under favored external conditions.
Deployable solar arrays are known in the art and are found in power supplies for space vehicles. The deployable solar arrays are typically stowed in a small container within their space vehicle during its launch, and are later deployed to an extended working configuration on the desired orbit. Examples of such arrays, in which pantograph like deployment mechanisms are used, can be found in the following United States patents: U.S. Pat. No. 3,460,992, issued to Avilov et al., U.S. Pat. No. 4,380,013 issued to Slysh, U.S. Pat. No. 5,131,955, issued to Stern et al., U.S. Pat. No. 5,487,791, issued to Everman et al., U.S. Pat. No. 5,961,738, issued to Benton et al., and U.S. Pat. No. 6,423,895, issued to Murphy et al. However, the deployable PV systems disclosed in the aforementioned patents were intended to be deployed as large satellite wings in weightless conditions on the orbit, which is not straightforwardly to be done on earth due to the fragility of the systems. In addition, only a single act of deployment was foreseen in the inventions, as is needed for a satellite, and no reference is made to a possibility of multiple retractions/deployments of a solar array.
U.S. Pat. No. 6,808,000, issued to Peterson, teaches a vertically movable mechanical curtain or partition utilizing a plurality of laterally spaced apart pantographs. This design resembles a honeycomb window shade, but is substantially larger. The partition is movable between a raised storage position and a lowered position. It is suggested that the fabric of the partition may be of a solar cell material that can convert light energy into electrical energy.